Looks like you have a lot or odds and ends, I can try my best to help clarify what goes with what if you want....
Fitteds work really well with pull-on covers, not so good with velcro or snap covers, although they will work, it's not the easy to fasten the diaper and then fasten the cover as well, plus it's much bulkier. Much easier to just pull one on.
Velcro or snap cover work great over Prefolds, contours or Flats.
I also second the suggestions to get a few more nb covers. The 4 wool nikkys will be nice, but once they get poopy and have to be washed they take a day or 2 to dry completely. That's why fitted diapers work soooooo well with wool, no poopy leaks! 6-10 covers is nice to have with prefolds. Might want to get 12 of the premie unbleached prefolds, they are a bit smaller and fit sooooo well in those first few weeks!
Our favorite combo with a nb was a nb sized fitted (anything like kissaluvs works great) and a simple pull-on cover. We swear by the Alexis Featherlite covers. They fit sooo well, left no red marks, were breathable, economical, and NO LEAKS! If you are planning on nursing and letting baby sleep with mommy, it's nice to have a system that doesn't leak at all for night time. Fitteds with pull-on covers seem to be the easiest for mommies to change in the middle of the night(daddies too, but you can only count on their help for so many changes, after about 2 wks daddies seem to peeter out, and it's up to us....lol!) I kept a small flashlight under the pillow and had all the diaper necessities(changing pad, prefolds for messes, fitteds, a cover or 2, Washable wet bag)on our nightstand, with a big glass of water for me too.
After that I loved the one-sized fitteds. They are a bit bulky on a nb, but they definatly do work. And once the nb fitteds were all dirty we used the one-sized fitteds until the laundry was done. Then as baby grew out of the nb fitteds, the one-sized kept going! It was that they ended up being less expensive than prefolds and covers over time too. Easier, cuter, breathable and cheaper. What could be better, lol!